Rotary vane pump

ABSTRACT

A rotary vane vacuum pump having a direct connection between a rotary motor and the vanes. The pump rotors are adapted to be submerged in oil and a unique noise suppressing device that permits oiling is employed on the outlet port. The same includes a flexible reed slightly spaced from the outlet port so that oil may be drawn in through the outlet port for lubrication purposes while suppressing the noise attendant the exit of gas therefrom at other points of the operating cycle.

Jan. 1, 1974 United States Patent [1 1 LeBlanc, Jr.

Joseph A. LeBIanc, Jr., Glen Ellyn, 11].

Inventor:

Attorney-Axel A. Hofgren et al.

[73] Assignee: Componetrol, Inc., Chicago, Ill.

Filed: Nov. 26, 1971 Appl. No.: 202,292

ABSTRACT A rotary vane vacuum pump having a direct connection between a rotary motor and the vanes. The pump jfigg rotors are adapted to be submerged in oil and a 418/83 unique noise suppressing device that permits oiling is Int Cl [58] Field of Search.........

employed on the outlet port. The same includes a flexible reed slightly spaced from the outlet oi port so that References Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 1 may be drawn in through the outlet port for lubrication purposes while suppressing the noise attendant 2,902,2l0 418/83 the exit of gas therefrom at other points of the 0 2,877,947 m Cyc]e 2,877,946

perat- Wessling et al..... Garrison et al.

4 Claims, 2 Drawing Figures l,l78,265 l/l970 Great Britain,....................... 418/83 PATENIEDJAM 11914 SHEEI 1 BF 2 x Q S g am 3 ROTARY VANE PUMP BACKGROUND OF THE INVENTION This invention relates to rotary vane pumps, and more specifically, rotary vane pumps employed for drawing vacuums.

Over the years, rotary vane pumps have been employed for drawing vacuums and have performed the task satisfactorily. However, a number of constructions are undesirable by reason of noise generated during the operation; bulk of construction; or the generation of a vaporized oil cloud after extended use.

One prior solution to the noise problem involves the employment of a valve at the outlet port, which valve I must'be capable of permitting gas to be exhausted as well as permitting inflow of oil to the pumping chamber for lubrication purposes. One construction heretofore known employed a slotted, resilient member overlying the outlet port with the sides of the member defined by the slot moving slightly inwardly into the port to permit the inflow of oil and moving outwardly to permit the outflow of gas. Such constructions, while satisfactory in suppressing noise and permitting accurate lubrication, are rather expensive tofabricate in view of tolerances required in forming the slot in the resilient member.

With regard to bulk of such pumping devices, prior art constructions generally have involved the employment of intermediate drive mechanisms, such as gears, interposed between. .the pump shaft and a suitable source of rotary motion, such as a motor. Obviously, the use of such intermediate drive mechanisms increases the bulk of a pump employing the same.

Finally, with regard to oil vapor clouds, after extended use, the oil in the pump will tend to heat up to the extent that some of the same vaporizes with the result that if the vapor is outletted into the area in which the pump is operating, very unsatisfactory working conditions may exist.

SUMMARY OF THE INVENTION It is the principal object of the invention to provide a new and improved rotary vane pump for use in drawing vacuums. More specifically, it is an object of the invention to provide such a pump including new and improved means for noise suppression while permitting adequate lubrication; a construction that eliminates any need for intermediate drive mechanisms between a source of power and the rotary pump; and a means for preventing the dissemination of oil vapor into the environment wherein the pump is employed. 1

The foregoing objects are accomplished by a pump construction which may include one or more stages, each having a customary pumping chamber with a rotor mounting at least one radially movable, outwardly biased beam within the chamber. The chamber includes a gas inlet as well as a gas outlet and is adapted to be totally submerged in oil. Noise at the outlet is suppressed, while rotor lubrication is permitted, by a flexible reed exterior of the pumping chamber and overly ing the outlet and separated therefrom by a small gap. According to one embodiment, the gap may be on the order of 0.0035 inches. The reed may move away from the outlet during the expulsion of gas and serves to suppress the noise of the same during that time while moving toward the outlet but not closing the same during a subsequent portion of a pumping cycle to permit the inflow of oil into the pumping chamber without significant noise.

To minimize bulk, the invention employs a rotor mounting shaft having an enlargedend with the recess therein for receiving the output shaft of a rotary motor. A unique arrangement of securing the motor to the pump housing and portions of the pump housing together permit the pump rotor to be directly connected to the output shaft of the motor for direct drive thereby eliminating any need for gear trains or the like while further eliminating the possibility of binding during operation due to misalignment.

Finally, the invention contemplates the provision of a filter-like element on a gas outlet from the housing which element agglomerates oil particles to preclude the emission of a vapor cloud of colloidal particles to the atmosphere surrounding the pump.

Other objects and advantages will become apparent from the following specification taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a pump made according to the invention with the pump shown in section; and

FIG. 2 is an exploded view of the major elements of the pump.

DESCRIPTION OF THE PREFERRED EMBODIMENT r An exemplary embodiment of a rotary vane pump for drawing a vacuumis illustrated in FIG. 1 and is seen to include a conventional electric motor 10 having a rotary output shaft 12. The motor 10 is secured to a pump casing generall y designated 14 by means of sleeve-like standoffs 16 having bolts within the same interconnecting the motor and the casing 14. The use of this construction permits some latitude in the position of the motor 10 with respect to the housing 14 to insure proper alignment to enable a direct coupling between the motor shaft 12 and the pumping elements.

Extending from the housing 14 in the direction of the motor 10 is an enlarged end 18 of a pump rotor shaft 20 and having an internal bore 22 receiving the motor shaft 12. An Allen screw 24 threaded through the shaft end 18 into engagement with a flat (not shown) on the motor shaft 12 secures the shaft 20 to the shaft 12 for rotation with the latter.

The housing 14 is defined by a front plate 26 and a rear casting 28 having an internal cavity 30 defining an oil reservoir. In normal operation, the cavity 30 is filled with oil to a level approximately equal to that designated by the numeral 32 and a sight glass 34 is located in the back side of the rear casting 28 for observing the oil level. An outlet valve 36 is also provided for draining oil from the cavity 30 if desired.

The front plate 26 is provided with a plurality of oil passages for lubrication or the like. For example, a pas sage 38 includes a downward extension 40 terminating in a circular groove 42 surrounding the shaft end 18 for communicating lubricating oil to that portion of the shaft journaled within the front plate 28. In actuality, the downward extension 40 is an outwardly opening groove in the face of the front plate 28 to seal the same, a seal plate 44 mounting a shaft seal 46 about the shaft end 18 is secured by a plurality of bolts 48 to the front side of the front plate 26 with a suitable gasket 50 inter posed therebetween.

The particular pump construction illustrated in FIGS. 1 and 2 is a two-stage pump and a pair of castings 52 and 54 respectively define first and second pumping stage chambers 56 and 58. The chambers 56 and 58 are separated by a plate 60 including a Z-shaped passage 62 extending from the outlet side of the first stage 56 to the inlet of the second stage 58 as will be seen.

Within the chambers 56 and 58 are identical rotors 64 keyed to the shaft by means of keys 66. Each of the rotors 64 mounts two diametrically opposed vanes 68 which are spring biased outwardly by a coil spring 70 surrounding an alignment pin 72, both of the latter being received in bores 74 extending through the shaft 20 and portions of the rotors 64. Preferably, the rotors 64 are force-fit on the shaft 20 resulting in a subassembly consisting of the shaft 20, the plate 60 and the rotors 64.

The leftmost chamber 58 illustrated in FIG. 1 is closed by an end plate 76 secured in the relation illustrated by means of bolts 78 extending through the same to be received in tapped bores in the front plate 26.

The casting 54 forming part of the second stage includes an outlet in its upper surface as will be seen and mounts an oil baffle 80 just above oil level to preclude oil from splashing upwardly towards an outlet (not shown) in the upper side of the casting 28. Encompassing the outlet is a sealing gasket 82. A condensing core 84 formed of a hollow cylinder of filter material or the like is held in sealing engagement with the gasket 82 by a can-like structure 86 having apertures 88 in its cylindrical surface. A screw 90 extends through an appropriate opening in the upper end of the can-like structure 86 to be received in a tapped bore 92 in the upper side of the casting 28. In operation, if the oil within the reservoir heats up to an extent that it begins to vaporize, the core 84 serves to condense such vapors and permit the oil to drain back into the reservoir so that an oil vapor cloud is not permitted to exit the pump structure to the surrounding environment.

Turning now to FIG. 2, the pumping chambers 56 and 58 will be described in greater detail. With reference to the pumping chamber 56, the same includes a pair of inlet ports 100 interconnected by a bore 102 and adapted, when assembled to the front plate 26, to be in fluid communication with a port 104 therein connected by a passage internal of the plate 26 to an inlet bore 106. The casting 54 is provided with similar interconnected inlet ports 108 which are aligned with one end of the Z-shaped passage 62.

Returning to the casting 52, the same includes a pair of exhaust ports 110, (only one of which is shown) interconnected by a bore 112 and so located as to be in fluid communication with the other end of the Z- shaped passage 62 in the plate 60. Exhaust ports in the casting 54 are defined similarly as indicated at 114. In addition, a vertical bore 116 in the casting 54 extends outwardly from the exhaust ports 114 into the reservoir 30.

As will be appreciated from the foregoing description, rotation of the rotor 64 is in a counterclockwise direction as viewed in FIG. 2 and the rotors are located eccentrically with respect to the chambers 56 and 58 such that the vanes 68 are at approximately their innermost point radially of the rotor 64 at a point of rotation intermediate the short distance between the associated inlet and exhaust ports and are at their radially outwardmost extent intermediate the long distance between the ports.

The exhaust bore 116 for the second stage opens on a step 118 in the casting 54. A flexible metallic reed 120 is secured to the upper surface of the casting 54 by means of a screw 122 and washer 124 impaled in a bore 126 in such a way such as to overlie the bore 116 and the step 118. As a result, a small space defined by the height of the step 118 exists between the outlet 116 and the reed 120 which permits a slight influx of oil from the reservoir into the pumping chamber 58 for a short period after a vane 68 moves past the exhaust port 114 toward the inlet port for lubrication purposes while suppressing noise during the remainder of the stroke when gas is expelled through the port 116. According to a preferred embodiment of the invention, the spacing between the reed 120 and the step 118 is on the order of 0.0035 inches. The pump is completed by an L-shaped handle 130 that may be threadedly received in a bore 132 in the front plate 26. In addition, a conventional valve member 134 is provided to regulate back pressure within the chamber so as to preclude substantial condensation of moisture therein.

It will be appreciated that the foregoing construction is extremely simple mechanically and does not require complex machining operations and/or close tolerances 'in fabrication of the reed 120. Thus, noise suppression and lubrication are achieved simultaneously with a relatively simple construction.

I claim:

1. A vacuum pump comprising:

a. means, including a block, defining a pumping chamber;

b. means defining a rotor for rotation within said chamber, said rotor including at least one radially movable, outwardly biased vane adapted to engage the wall of the chamber;

c. means mounting said rotor for rotation within said chamber about an axis displaced from the center of the chamber;

d. means defining a gas inlet in said chamber;

e. means defining a gas outlet in said chamber and spaced from said gas inlet and including an opening in said block;

f. means for rotating said rotor;

g. said gas inlet and said gas outlet being located about said chamber and arranged with respect to the axis of rotation of said rotor such that said vane will initially move outwardly and then inwardly as said vane is rotated from said gas inlet to said gas outlet;

h. means defining an oil reservoir encompassing said chamber such that when the oil reservoir is filled, the chamber will be submerged; and

i. a noise suppressor associated with said outlet comprising a flexible reed exterior of said chamber and within said reservoir adjacent said outlet and separated therefrom by a small gap, said small gap being defined by a relieved step in said block at least partially encompassing said opening, said reed being secured to said block remote from said opening and having a free end overlying said opening.

2. A two-stage vacuum pump employing the pump of claim 1 as the second stage thereof and further including a second of said pumping chambers and a second of said rotors; said mounting means additionally mounting said second rotor for rotation in said second chamber about an axis displaced from the center of said second chamber, a gas inlet in said second chamher; a gas outlet in said second chamber; and means connecting said second chamber gas outlet to said first chamber gas inlet.

3. The pump of claim 1 wherein said means for rotat- 

1. A vacuum pump comprising: a. means, including a block, defining a pumping chamber; b. means defining a rotor for rotation within said chamber, said rotor including at least one radially movable, outwardly biased vane adapted to engage the wall of the chamber; c. means mounting said rotor for rotation within said chamber about an axis displaced from the center of the chamber; d. means defining a gas inlet in said chamber; e. means defining a gas outlet in said chamber and spaced from said gas inlet and including an opening in said block; f. means for rotating said rotor; g. said gas inlet and said gas outlet being located about said chamber and arranged with respect to the axis of rotation of said rotor such that said vane will initially move outwardly and then inwardly as said vane is rotated from said gas inlet to said gas outlet; h. means defining an oil reservoir encompassing said chamber such that when the oil reservoir is filled, the chamber will be submerged; and i. a noise suppressor associated with said outlet comprising a flexible reed exterior of said chamber and within said reservoir adjacent said outlet and separated therefrom by a small gap, said small gap being defined by a relieved step in said block at least partially encompassing said opening, said reed being secured to said block remote from said opening and having a free end overlying said opening.
 2. A two-stage vacuum pump employing the pump of claim 1 as the second stage thereof and further including a second of said pumping chambers and a second of said rotors; said mounting means additionally mounting said second rotor for rotation in said second chamber about an axis displaced from the center of said second chamber, a gas inlet in said second chamber; a gas outlet in said second chamber; and means connecting said second chamber gas outlet to said first chamber gas inlet.
 3. The pump of claim 1 wherein said means for rotating said motor comprises a motor having a rotary outlet shaft directed along said axis.
 4. The vacuum pump of claim 1 wherein said relieved step only partially encompasses said opening. 